There are plenty of obvious signs that an item in your pantry or fridge has gone bad — if it's stale, moldy, or smells sour or rancid, you know to toss it in the trash. But there are several subtle signs your food has expired that you might not even notice, but definitely should because it could unknowingly be dangerous to consume.

INSIDER spoke with two chefs and a registered dietitian who gave us the scoop on the super subtle signs those kitchen staples have already begun to go bad, and some of them might surprise you.

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Check potatoes for a greenish tint.

Potatoes are one of the most versatile veggies out there, and their sturdiness might have you believing that they last much longer than other items in the produce aisles. But once your potato takes on a slight color change, you might want to toss it.

"The green tint in potatoes is not from age," said Isabel Maples, MEd, RDN, a Virginia-based registered dietitian nutritionist and volunteer spokesperson for the Academy of Nutrition and Dietetics. "It comes from them being near the surface of the earth and being exposed to sunlight, causing a buildup of a compound called solanine."

The greenish hue means your potato is beginning to go bad, but Maples said it can still be safe to eat. "Just peel off the green before eating the potato — It can taste bitter and can cause illness if eaten in large amounts. As potatoes get older, their texture becomes less firm, sometimes wrinkly. They start growing sprouts at the eyes. Just cut the eyes out before cooking to eat. Eventually, potatoes do develop soft spots, rot and stink," at which point, they're past the point of no return.

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Vegetables will begin "sprouting."

If you spot sprouts on your onions, it's best to toss them.
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If your potatoes, peppers, or onions begin sprouting, it's time to toss them, according to Alisa Rosa, an executive chef, who notes that a good rule of thumb is: "If they have sprouted, they have gone too far."

Those fresh fruits and veggies — like tomatoes, peppers, and berries — aren't so fresh anymore if they've developed wrinkled or peeling skin or have started to go soft and shrivel, according to Rosa.

"Natural foods are very good at letting us know when they are fresh and when they are beginning to start to decompose," she told INSIDER. "Decomposition is a natural process by which the product starts to literally go back to the earth. The tomato's job is to reproduce and it does this by decomposing and releasing its seeds back into the earth so that a new fruit may be produced. Though sometimes a little smelly and pretty gross to look at, if you think about it, it really is a perfect, beautiful process … The literal circle of life."

If they've begun to "weep some moisture," they will need to be tossed promptly, according to Rosa, because this marks the beginning stages of mold growth.

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Crisp veggies will take on a new texture.

You want your carrots to still be crunchy.
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Your zucchini, carrots, and celery "will start to lose their crispness and will become more rubbery" when they're going bad, according to Rosa.

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Seafood will smell fishy.

It might seem counterintuitive — of course, fish should smell like fish, right? Wrong, according to all three of our experts, who told us that a particularly "fishy" odor means your seafood is already going bad.

"Fresh fish should smell a little like the ocean," explained Tryg Siverson, chef and co-founder, COO and culinary director of Feel Good Foods. "The fishier the smell, the longer it's been out of the water."

"Truly fresh fish will have an almost sweet, clean, ocean smell," added Rosa.

If you have a whole fish, Maples added another way to tell if it's actually fresh — "If it's a whole fish with eyes, the eyes should be clear, not glassy," she said, adding that seafood will also "start getting a slimy feel," at which point, it's time to toss it.

Canned goods should not be bent, dented, corroded, or swollen.

You might not think that the outside of a can has any indication of the freshness of what's inside, but it's true — all three of our experts agree that it's safer to get rid of any container that has any sort of hole, corrosion, or swelling.

"Bent or dented cans of food are always advised to be discarded," explained Siverson. "The dented can could have a microscopic hole that is allowing the food to be exposed to oxygen and giving bacteria an environment to thrive in."

Rosa agreed, adding, "If you ever come across [a food product whose container (either a can, box, or bottle) that has any moisture in it and the container looks bloated or swollen — or when you open the container, a large amount of air escapes — it should be thrown out.] This is a subtle sign of botulism, the most dangerous foodborne illness."

Maples cited both dairy and non-dairy milk as examples of the most dangerous to consume, telling us that "once a container is bloated, it is way past the point of anyone wanting to drink it."

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Frozen items will develop ice crystals or frost.

Be on the lookout for frost, especially on meats and fish.
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It might seem like frozen foods covered in crystals or frost means that the food has been kept very cold, but it's exactly the opposite, according to our experts.

Ice crystals inside a package mean that the food is starting to go bad, said Rosa. "If you can't see what the item is, it's time to trash it."

Siverson agreed, adding, "Frozen food caked with ice crystals is a sign that there has been temperature abuse, meaning the food probably came up above freezing and then was re-frozen."

Expired baking soda won't be as fizzy.

Baking soda is perhaps one of the most versatile pantry staples, but that doesn't mean it lasts forever … and it can be hard to tell whether or not the one you've got is still fresh.

But Siverson told us that "baking soda can easily be tested to see if it is still good. Add a tablespoon to a bowl and pour in a little white vinegar. If it fizzes rapidly, it is still good. If not, then throw it away."

Maples recommends mixing with warm water and should be used within three years of opening, though added that "discriminating bakers recommend using up baking powder within nine months of opening the container."

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Changes in scent are often a surefire way to tell if something is still fresh.

Having a discerning sense of smell helps more than you'd think, because often times, foods will begin smelling "off" as they're beginning to expire, even if they look fine.

"When in doubt, follow your nose," said Siverson. "Your nose does a great job of keeping you away from dangerous foods. If your olive oil doesn't smell like olives anymore, it is probably not in its freshest state."

"The number one rule is: If it doesn't smell so good that you want to eat it, it's probably past its prime," added Rosa. "Spices and herbs should be fragrant. Nothing should smell 'stale' or 'old.'"